Controlled high pressure separator for production fluids

Abstract

A controlled production fluids separator. The separator is configured to be placed in fluid communication with a production fluids flow line coming off of a well head. The separator includes an inlet configured to receive fluids from the flow line. The separator has a water dump valve and an oil dump valve. The separator further has a gas outlet residing along the upper surface of the vessel. The gas outlet comprises a valve configured to open and close in response to control signals. In this way, the valve serves as a back-pressure regulator valve for the separator. The separator also includes a controller. The controller is configured to periodically receive data indicative of fluid flow through the flow line, and adjust a back-pressure setpoint in real time by sending signals to the back-pressure regulator valve for opening and closing. A method of operating a three-phase production fluids separator is also provided.

I claim: 
     
       1. A fluids separator, comprising:
 a wall having an inlet end, an upper surface and a lower surface; 
 an inlet in the wall configured to receive production fluids from a flow line associated with a well head; 
 a gas outlet residing along the upper surface of the wall, the gas outlet comprising a valve configured to open and close in response to control signals sent by a controller, wherein the valve serves as a back-pressure regulator valve for the separator; 
 a water dump valve residing along the lower surface of the vessel, the water dump valve comprising an actuator configured to open and close the water dump valve in response to water level control signals generated by a level control sensor in a water zone within the fluids separator; 
 an oil dump valve also residing along the lower surface of the vessel, the oil dump valve comprising an actuator configured to open and close the oil dump valve in response to oil level control signals generated by a level control sensor in an oil zone within the fluids separator; and 
 the controller, wherein:
 the controller is configured to periodically receive separator data from sensors indicative of fluid flow through the flow line, and adjust a pressure setpoint for the back-pressure regulator valve in real time by sending signals P B  to the back-pressure regulator valve for opening and closing the gas outlet, such that:
 when the controller determines that the separator data is indicative of a rising level of oil and water in the separator, the controller sends a signal to increase the pressure setpoint for the back-pressure regulator valve; and 
 when the controller determines that the separator data is no longer indicative of a rising level of oil and water in the separator, the controller sends a signal to decrease the pressure setpoint for the back-pressure regulator valve; 
 
 
 thereby controlling back-pressure in the separator and limiting emergency shut-downs (“ESD's”) at the well head. 
 
     
     
       2. The fluids separator of  claim 1 , wherein:
 the separator is a three-phase fluid separator; 
 the separator further comprises a high liquid-level shutdown switch; 
 the inlet is at or proximate the inlet end; and 
 the flow line receives the production fluids from a production tubing below the well head; 
 and wherein the high liquid-level shutdown switch is configured to send an emergency shutdown (“ESD”) signal to the well head when oil and water within the separator together reach a designated level. 
 
     
     
       3. The fluids separator of  claim 2 , wherein the wall forms a horizontal pressure vessel. 
     
     
       4. The fluids separator of  claim 2 , wherein the separator data comprises:
 (i) signals generated by a pressure transducer located along the flow line at or near the well head; 
 (ii) signals generated by a pressure transducer in the separator; 
 (iii) the oil level control signals generated by the level control sensor within the oil zone; 
 (iv) the water level control signals generated by the level control sensor within the water zone; 
 (v) signals generated by a flowmeter at the oil dump valve; 
 (vi) signals generated by a flowmeter at the water dump valve; or 
 (vii) combinations thereof. 
 
     
     
       5. The fluids separator of  claim 4 , wherein periodically receiving the separator data means receiving the signals every ½ to 30 seconds. 
     
     
       6. The fluids separator of  claim 4 , wherein the controller is further configured to record instances where the ESD signals are sent. 
     
     
       7. The fluids separator of  claim 4 , wherein: the back-pressure regulator valve comprises:
 a solenoid; and 
 two pressure controllers, wherein a first pressure controller operates at a first pressure setpoint and a second pressure controller operates at a second pressure setpoint, wherein the second pressure setpoint is higher than the first pressure setpoint; 
 and wherein:
 when the controller determines that the separator data is indicative of a rising level of oil and water in the separator, the controller is configured to send a signal to the solenoid to actuate the second pressure controller to operate the back-pressure regulator valve at the second pressure setpoint; and 
 when the controller determines that the data is no longer indicative of a rising level of oil and gas in the separator, the controller is configured to send a signal to the solenoid to actuate the first pressure controller to operate the back-pressure regulator valve at the first pressure setpoint. 
 
 
     
     
       8. The fluids separator of  claim 7 , wherein actuating the first pressure controller to operate the back-pressure regulator valve at the first pressure setpoint comprises slowly returning the separator from the second pressure setpoint to the first pressure setpoint. 
     
     
       9. The fluids separator of  claim 7 , wherein the back-pressure regulator valve further comprises a differential pressure controller configured to limit opening of the back-pressure regulator valve at the gas outlet when transitioning the separator from the second pressure setpoint back to the first pressure setpoint, thereby preventing sudden pressure drops in the separator during the transitioning. 
     
     
       10. The fluids separator of  claim 4 , wherein:
 the back-pressure regulator valve comprises:
 an I to P transducer; and 
 a motor valve that provides variable pressure setpoints for the separator in response to signals from the controller. 
 
 
     
     
       11. The fluids separator of  claim 4 , further comprising:
 the pressure transducer located at the separator and configured to transmit signals (P S ) to the controller indicative of pressure within the separator; and 
 the pressure transducer located along the flow line proximate the well head and configured to transmit signals (P F ) to the controller indicative of pressure along the flow line, and wherein the controller is configured to:
 receive signals (P S ) and (P F ) as separator data indicative of fluid flow through the flow line; 
 periodically calculate a pressure differential between (P S ) and (P F ) as (ΔP); 
 determine whether the (ΔP) calculations are indicative of a post liquid slug gar release (“PLSGR”) event; and 
 if a PLSGR event is indicated, send a signal to the back-pressure regulator valve to increase the pressure setpoint, thereby increasing the pressure on the separator and flow line. 
 
 
     
     
       12. The fluids separator of  claim 11 , wherein a PLSGR event is indicated if (ΔP) is greater than 40 psi. 
     
     
       13. The fluids separator of  claim 11 , wherein a PLSGR event is indicated if the controller receives signals (P F ) that exceed six standard deviations. 
     
     
       14. The fluids separator of  claim 4 , wherein:
 the level control sensor in the oil zone comprises a throttling controller that generates a pressure signal (L O ) indicative of oil level within the separator; 
 the level control sensor in the water zone comprises a throttling controller that generates a pressure signal (L W ) indicative of water level within the separator; and 
 the controller is configured to receive the pressure signals (L O ), (L W ) from the throttling controllers of the level control sensors as at least part of the separator data. 
 
     
     
       15. The fluids separator of  claim 14 , wherein the controller is further configured to:
 periodically compare the (L O ) and (L W ) data with average oil level and water level values, respectively; and 
 upon determining that the oil level and the water level have each returned to average values, send a signal to the back-pressure regulator valve to lower the pressure setpoint, thereby decreasing the pressure on the flow line. 
 
     
     
       16. The fluids separator of  claim 15 , wherein lowering the pressure setpoint comprises (i) lowering the pressure setpoint to a pre-programmed operating setpoint, or (ii) incrementally lowering the pressure setpoint towards a minimum pressure setpoint until the controller again receives data indicative of rising level of oil and water in the separator. 
     
     
       17. The fluids separator of  claim 2 , wherein:
 the separator data comprises:
 (i) signals generated by a pressure transducer located along the flowline at or near the well head; 
 (ii) signals generated by a pressure transducer in communication with the separator; 
 (iii) the oil level control signals generated by the level control sensor within the oil zone; and 
 (iv) the water level control signals generated by the level control sensor within the water zone; and 
 
 
       the controller is further configured to:
 receive signals (L O ) from the level control sensor in the oil zone and signals (L W ) from the level control sensor in the water zone; 
 compare the (L O ) and (L W ) signals with pre-set oil level (T O-A ) and pre-set water level (T W-A ) values, respectively; and 
 based upon these comparisons, upon determining that the oil level and the water level have returned to at least the pre-set values (T O-A ), (T W-A ), send a signal to the back-pressure regulator valve to lower the pressure setpoint, thereby decreasing back-pressure on the flow line. 
 
     
     
       18. The fluids separator of  claim 17 , wherein the controller is further configured to:
 monitor (L O ) and (L W ) signals to determine whether the oil and water levels within the separator are rising; and 
 upon determining that the oil level and the water level are rising, send a signal to the back-pressure regulator valve to increase the pressure setpoint. 
 
     
     
       19. A method of operating a production fluids separator comprising:
 providing a production fluids separator, the production fluids separator comprising:
 a wall having an inlet end, an upper surface and a lower surface; 
 an inlet at the inlet end configured to receive production fluids from a flow line extending from a well head; 
 a gas outlet residing along the upper surface of the vessel, the gas outlet comprising a valve configured to open and close in response to control signals, wherein the valve serves as a back-pressure regulator valve for the separator; 
 a water dump valve residing along the lower surface of the vessel, the water dump valve comprising an actuator configured to open and close the water dump valve in response to level control signals generated by a level control sensor in a water zone within the fluids separator; 
 an oil dump valve also residing along the lower surface of the vessel, the water dump valve comprising an actuator configured to open and close the oil dump valve in response to level control signals generated by a level control sensor in an oil zone within the fluids separator; and 
 a controller, wherein the controller is configured to periodically receive separator data indicative of fluid flow through the flow line, and adjust a pressure setpoint for the back-pressure regulator valve in real time by sending signals (P B ) to the back-pressure control valve for opening and closing the gas outlet; 
 
 placing the inlet of the separator in fluid communication with the flow line, with the well head receiving production fluids from a production tubing within a wellbore; 
 when the controller determines that the separator data is indicative of a rising level of oil and water in the separator, sending a signal to increase the pressure setpoint for the back-pressure regulator valve; and 
 when the controller determines that the separator data is no longer indicative of a rising level of oil and water in the separator, sending a signal to decrease the pressure setpoint for the back-pressure regulator valve; 
 thereby controlling back-pressure and limiting emergency shut-downs (“ESD's”) at the well head. 
 
     
     
       20. The method of  claim 19 , wherein:
 the separator is a three-phase fluid separator; 
 the separator further comprises a high liquid-level shutdown switch; 
 and 
 the wall forms a horizontal pressure vessel; 
 and wherein the high liquid-level shutdown switch is configured to send an emergency shutdown (“ESD”) signal to the well head when oil and water within the separator together reach a designated level. 
 
     
     
       21. The method of  claim 20 , wherein the production fluids flowing through the flow line comprise methane and any of (i) ethane, (ii) propane, (iii) butane, (iv) pentane, (v) hexanes and other higher chain hydrocarbons, (vi) carbon dioxide, (vii) nitrogen, (viii) hydrogen sulfide, or (ix) combinations of (i) through (viii). 
     
     
       22. The method of  claim 20 , wherein the separator data comprises:
 (i) signals generated by a pressure transducer located along the flow line at or near the well head; 
 (ii) signals generated by a pressure transducer in communication with the separator; 
 (iii) the level control signals generated by the level control sensor within the oil zone; 
 (iv) the level control signals generated by the level control sensor within the water zone; 
 (v) signals generated by a flowmeter at the oil dump valve; 
 (vi) signals generated by a flowmeter at the water dump valve; or 
 (vii) combinations thereof. 
 
     
     
       23. The method of  claim 22 , wherein periodically receiving the data means receiving the signals every ½ to 30 seconds. 
     
     
       24. The method of  claim 22 , wherein:
 the back-pressure regulator valve comprises: 
 a solenoid; and 
 two pressure controllers, wherein a first pressure controller operates at a first pressure setpoint and a second pressure controller operates at a second pressure setpoint, wherein the second pressure setpoint is higher than the first pressure setpoint; 
 and wherein:
 when the controller determines that the separator data is indicative of a rising level of oil and water in the separator, the controller is configured to send a signal to the solenoid to actuate the second pressure controller to operate the back-pressure regulator valve at the second pressure setpoint; and 
 when the controller determines that the separator data is no longer indicative of a rising level of oil and water in the separator, the controller is configured to send a signal to the solenoid to actuate the first pressure controller to operate the back-pressure regulator valve at the first pressure setpoint. 
 
 
     
     
       25. The method of  claim 24 , wherein actuating the first pressure controller to operate the back-pressure regulator valve at the first pressure setpoint comprises slowly returning the separator from the second pressure setpoint to the first pressure setpoint. 
     
     
       26. The method of  claim 21 , further comprising:
 providing a pressure transducer located at the separator and configured to transmit signals (P S ) to the controller indicative of pressure within the separator; and 
 providing a pressure transducer along the flow line proximate the well head configured to transmit signals (P F ) to the controller indicative of flow line pressure; 
 and wherein the controller is configured to:
 receive signals (P S ) and (P F ) as separator data indicative of fluid flow through the flow line; periodically calculate a pressure differential between (P S ) and (P F ) as (ΔP); 
 determine whether the (ΔP) calculations are indicative of a post liquid slug gas release (“PLSGR”) event; and 
 upon determining that a PLSGR is about to occur, send a signal to the back-pressure regulator valve to increase the pressure setpoint, thereby increasing the pressure on the flow line. 
 
 
     
     
       27. The method of  claim 26 , wherein a PLSGR event is indicated if (ΔP) is greater than 40 psi. 
     
     
       28. The method of  claim 20 , wherein:
 a throttling oil level controller generates a pressure signal (L O ) indicative of oil level within the separator; 
 a throttling water level controller generates a pressure signal (L W ) indicative of water level within the separator; and 
 the controller is configured to receive the pressure signals (L O ), (L W ) from the throttling oil level and water level controllers, respectively, as the separator data. 
 
     
     
       29. The method of  claim 28 , wherein the controller is further configured to:
 receive signals (L O ) and (L W ) as data indicative of fluid flow through the flow line; 
 periodically compare (L O ) and (L W ) data with average oil level and water level values within the separator, respectively; and 
 upon determining that the oil level and the water level have each returned to their average values, send a signal to the back-pressure regulator valve to lower the pressure setpoint, thereby decreasing the pressure on the flow line. 
 
     
     
       30. The method of  claim 29 , wherein lowering the pressure setpoint comprises (i) lowering the pressure setpoint to a pre-programmed operating setpoint, or (ii) incrementally lowering the pressure setpoint towards a minimum pressure setpoint until the controller again receives data indicative of rising level of oil and water in the separator. 
     
     
       31. The method of  claim 20 , wherein:
 the oil dump valve comprises a flowmeter for measuring volumes of fluid (F O ) passing through the oil dump valve for a period of time, and periodically sending signals to the controller indicative of (F O ); and 
 the water dump valve comprises a flowmeter for measuring volumes of fluid (F W ) passing through the water dump valve for the period of time, and periodically sending signals to the controller indicative of (F W ); and 
 the method further comprises:
 comparing (F O ) with a volume of oil (F O-A ) that should pass through the oil dump valve in the period of time based upon a detected number of times the oil dump valve has released oil (“oil dump incidents”) multiplied by an anticipated oil volume release per oil dump incident; 
 upon determining that (F O ) is greater than (F O-A ), sending an alert signal to an operator that trim associated with the oil dump valve is in need of repair or replacement; 
 comparing (F W ) with a volume of water (F W-A ) that should pass through the water dump valve in the period of time based upon a detected number of times the water dump valve has released water (“water dump incidents”) multiplied by anticipated water volume release per water dump incident; and 
 upon determining that (F W ) is greater than (F W-A ), sending an alert signal to an operator that trim associated with the water dump valve is in need of repair or replacement. 
 
 
     
     
       32. The method of  claim 31 , further comprising:
 in response to receiving an alert signal, replacing trim associated with the oil dump valve, replacing trim associated with the water dump valve, or both. 
 
     
     
       33. The method of  claim 19 , wherein:
 the back-pressure regulator valve comprises:
 an I to P transducer; and 
 a motor valve that provides variable back-pressure setpoints for the separator in response to control signals from the separator. 
 
 
     
     
       34. The method of  claim 19 , wherein the controller is further configured to record instances where the ESD signals are sent.